package configs

import (
	"errors"
	"os"
	"path/filepath"

	"github.com/iwind/TeaGo/Tea"
	"gopkg.in/yaml.v3"
)

const ConfigFileName = "api_httpdns.yaml"
const oldConfigFileName = "api.yaml"

var sharedAPIConfig *APIConfig

type APIConfig struct {
	OldRPC struct {
		Endpoints     []string `yaml:"endpoints"`
		DisableUpdate bool     `yaml:"disableUpdate"`
	} `yaml:"rpc,omitempty"`

	RPCEndpoints     []string `yaml:"rpc.endpoints,flow" json:"rpc.endpoints"`
	RPCDisableUpdate bool     `yaml:"rpc.disableUpdate" json:"rpc.disableUpdate"`

	NodeId string `yaml:"nodeId"`
	Secret string `yaml:"secret"`

	ListenAddr string `yaml:"listenAddr"`

	HTTPSListenAddr string `yaml:"https.listenAddr" json:"https.listenAddr"`
	HTTPSCert       string `yaml:"https.cert" json:"https.cert"`
	HTTPSKey        string `yaml:"https.key" json:"https.key"`

	LogDir string `yaml:"logDir" json:"logDir"`
}

func SharedAPIConfig() (*APIConfig, error) {
	if sharedAPIConfig != nil {
		return sharedAPIConfig, nil
	}

	config, err := LoadAPIConfig()
	if err != nil {
		return nil, err
	}
	sharedAPIConfig = config
	return config, nil
}

func LoadAPIConfig() (*APIConfig, error) {
	for _, filename := range []string{ConfigFileName, oldConfigFileName} {
		var loadedData []byte
		var loadedPath string
		for _, candidate := range findConfigCandidates(filename) {
			data, err := os.ReadFile(candidate)
			if err != nil {
				if os.IsNotExist(err) {
					continue
				}
				return nil, err
			}
			loadedData = data
			loadedPath = candidate
			break
		}

		if len(loadedData) == 0 {
			if filename == oldConfigFileName {
				continue
			}
			return nil, errors.New("no config file '" + ConfigFileName + "' found")
		}

		config := &APIConfig{}
		err := yaml.Unmarshal(loadedData, config)
		if err != nil {
			return nil, err
		}

		err = config.Init()
		if err != nil {
			return nil, err
		}

		if filename == oldConfigFileName {
			config.OldRPC.Endpoints = nil
			// 优先写回当前旧配置所在目录，避免依赖启动时工作目录
			_ = config.WriteFile(filepath.Join(filepath.Dir(loadedPath), ConfigFileName))
		}

		return config, nil
	}
	return nil, errors.New("no config file '" + ConfigFileName + "' found")
}

func (c *APIConfig) Init() error {
	if len(c.RPCEndpoints) == 0 && len(c.OldRPC.Endpoints) > 0 {
		c.RPCEndpoints = c.OldRPC.Endpoints
		c.RPCDisableUpdate = c.OldRPC.DisableUpdate
	}

	if len(c.RPCEndpoints) == 0 {
		return errors.New("no valid 'rpc.endpoints'")
	}

	if len(c.NodeId) == 0 {
		return errors.New("'nodeId' required")
	}
	if len(c.Secret) == 0 {
		return errors.New("'secret' required")
	}

	// 兼容旧配置中的 listenAddr
	if len(c.HTTPSListenAddr) == 0 {
		if len(c.ListenAddr) > 0 {
			c.HTTPSListenAddr = c.ListenAddr
		} else {
			c.HTTPSListenAddr = ":8443"
		}
	}

	if len(c.HTTPSCert) == 0 {
		// return errors.New("'https.cert' required")
	}
	if len(c.HTTPSKey) == 0 {
		// return errors.New("'https.key' required")
	}
	return nil
}

func (c *APIConfig) WriteFile(path string) error {
	data, err := yaml.Marshal(c)
	if err != nil {
		return err
	}
	return os.WriteFile(path, data, 0666)
}

func findConfigCandidates(filename string) []string {
	candidates := []string{
		Tea.ConfigFile(filename),
		Tea.ConfigFile(filepath.Join("configs", filename)),
		filename,
		filepath.Join("configs", filename),
	}

	if exePath, err := os.Executable(); err == nil {
		exeDir := filepath.Dir(exePath)
		candidates = append(candidates,
			filepath.Join(exeDir, filename),
			filepath.Join(exeDir, "configs", filename),
			filepath.Join(exeDir, "..", "configs", filename),
		)
	}

	uniq := map[string]struct{}{}
	result := make([]string, 0, len(candidates))
	for _, candidate := range candidates {
		candidate = filepath.Clean(candidate)
		if len(candidate) == 0 {
			continue
		}
		if _, ok := uniq[candidate]; ok {
			continue
		}
		uniq[candidate] = struct{}{}
		result = append(result, candidate)
	}
	return result
}